Grinding apparatus



May 9, 195o A. J. BRUNNER ET AL 2,507,298

GRINDING APPARATUS May 9, 1950 A. J. BRUNNl-:R ET AL GRINDING APPARATUS 4 Sheets-Sheet 2 Filed Oct. lO, 1945 May 9, 1950 A. J. BRUNNER ET AL GRINDING APPARATUS 5 R6 vl s 5MM h TNB an QW NURL@ Mm WMEZW m Mdm A s t S W. A

W. WM... Ich. l m. WAK d May 9, 1950 A. J. BRUNNER ET Ax. 2,507,298

GRINDING APPARATUS Filed Oct. l0, 1945 4 Sheets-Sheet 4 Patented May 9, 1950 oNlrso STATES PATENT orties Application Octber 10, 1945 Stri'lalNo 6221,5,81

This invention relates to grinding apparatus and more particularly to an apparatus for suri face grinding flexible strip rnaterial to predet'erf mined thickness. i

r'Ihe invention is particularly useful in grinding fiat insulatorcores or cards to be subsequently shaped and Wound with vWire to provide resistances for use in potentiometers of the type used in radar equipment. Such cards may comprise fiat relatively thin strips 'of phenol bre or rubber, some types of which are from 30 to 60" in length. In order to Wind such resistance cards with accuracy, it is very necessary that the blanks from which the cards are shaped be ground to a high degree of precision'and a required uniform thickness throughout their length. An object of the present invention is the provision of a practicable and eiiicient apparatus for grinding flexible strip material with precision and a required uniform thickness.

c claims. (Cl. 51-110) Fig. 1 is a fragmentary front elevational View of `a` grinding apparatus 'embodying the features of this"inverltiorr;r A

` Fig'f`2 is a fragmentary vertical section, partly in elevation, taken'on the lines 2-2 of Fig. l;

f "'Fig." B'is'an enlarged fragmentary vertical section taken on the lines .1i- 3 f 2;

Fig'lfi isa "fragmentary plan view, partly in sectim,l taken on'rthe `lines lil-lll of Fig. Stand HVFig. 5 is an enlarged detail plan 'section taken on the lines 5,--5 of Fig. l.

in accordance withl one embodiment of the "f invention, which is illustrated herein as applied to the grinding of insulator card'blanls, referred to above. to predetermined thicknesses, a grinding apparatus is provided which includes a cupshaped rotatable grinding'yvheel having an annular "abrasive'face for engaging the face cfa card blank to be ground, which is being fed across a backing'plate in a direction pe'rpendicf'A ular to the axis'of the Wheel, rotatable in a fixed position, by cooperating pairs of feed rollers, one set at each side ofthe Wheel, the pair of rollers at the exit end of the apparatus being in a different horizontal plane'than the rollers at the entrance end'so that only an are or portion of the annularv abrasive face of the Wheel adjacent the entrance end is effective to grind the card blank. The rollers of each pair are positively driven, one roller being operatively yieldably Ar'nounlted relative thereto. For' the ypurpose "of feeding the card blank under desired longitudinal tension during its grinding,therollers at lthe exit end havev aslightly larger periphery than the rollers at the entrance end. Guide means for the card blank are provided for directing it between" the Vfeedrollers at the'entrance'end and adjacent each sideof the portion of the annular abrasive face of the wheel Which engages the card blanlofor guiding the blank between the abrasive face andthebaeking plate and thence in an inclined plane to and betwenthe'feed vrollf ers at the'exit end, The feed rollers, guide means and backing plate are mounted for unitary move'- rnent upon anv adjustable"framewhereby, as the annular abrasivefaeeof the grinding Wheel Wears and is dressed, theseelernents may be /moved Referring'to the drawings and particularly to Figs. l and 2, the 'numeral I0 indicates, in general, a 'iedfrarne cornprising two/spaced standar'ds Il supported at their l'o'iver'ends on a suitable base (not s hovvnl'. yFixed to and interconnectirg the standards H are spaced horizontal 6rosfsinernbers' i2, itand I 4. Carried upon the rneniber"lfinterinediate thestandards il isa-n electric motor "ffl having its driving shaft I8 (Figs."2 and '3)"vertically disposed and having fired thereto at its'loWer en`d 'an inverted cup shaped" grinding Wheel i9 Iinade of a suitable abrasive material, its 'lower annular face 2G engaging the uppierrfavo'e of a strip of material or, inthe presente instance, a card blank 2| (Fig. 3) vvhichisv tobe ground vtoa predetermined thickness.

` Arranged beto/ een the cross members l2 and lois an" irregular shaped vertically adjustable hollow 'frame "2!lf'ergtendin'g perpendicular to the axis of rotation of 'the grinding Wheel I9 and hav'- ing three v"oompa,rtnit-ints 25;, '2S and 2l open yat their tops. Attached:to a central bearing portionf28` -of thejframe; 24 in axial alignment with the grindingfwheel IQ `and depending therefrom is 'a holloivguidepost 3 l ,circular 'in cross-section, and ',slldably fitted in: the` cross members i3 and is." ySecuredto the upper annular face of the bearing" portion 2 8 is a cap `plate 32, the upper fend face `of, 'the post 3l abutting a lower recessed face ofthe plate. Fixed tov and depending from the'bearingportion 2t" at itsright side (Figs. l, 2 and 3) 'is V(a rodr 'lill having its 'lower `end screwtlireaded ,(FigJfZ) `vands lidably fitted in the cross member* i3 and ini'an irregular shaped hollow f standard 3d carried upon "the cross member Ui.

Rotatable upon the screw-threaded kportion of the rod 33 isla circular nut Sthavin'g formed' on itsA periphery'vvorm gear teeth which mesh with aworrn 3B 'xe'dto 'a'shaft' 39 journalled in the dard 3.4, the nut'being prevented from mov-l upivardlyor downwardly upon the rod 3S durme its it. on since irisY confined by abutting l'fsacesof 'thecross member I3 and the standard Fixed. :totheouter en d of the shaft 3S, (Fig. 1l is a'lfland Wheel 4B.' Also fixed to Vand depending 4from the bearing portion 28 at its left side (Figsj l and 3) visfa rodl, slidably tted in the cross uiernber i3 and having screw-threaded onto its-slower end betr the cross member I3 is a par of stop nuts 42. It will be apparent, for a purpose to be referred to hereinafter, that upon rotating the hand wheel 40 in one direction or the other, the frame 24 may be adjusted upwardly or downwardly relative to the grinding wheel I9. Upon the frame 24 being properly adjusted, the stop nuts 42 are rotated on the rod 4| into operative stop relation with the bottom face of the cross member |3, thus preventing accidental upward movement of the frame after its adjustment. In order to lock the frame 24 from accidental movement either upwardly or downwardly after its adjustment, the guide post 3| is clamped to the cross member |3 by ya pair of opposed shoes 45 and 46 (Fig. 5) longitudinally slidable in the cross member and formed with arcuate faces 41 engaging the peripheral face of the post 3|. Fixed to the shoe 45 is a rod 48, which extends freely through the shoe 46 and is screwthreaded at its outer end, upon which end is screw-threaded a handle 49. By rotatingr the handle 49 in one direction, the shoes 45 and 46 are drawn into clamping engagement with the post 3|, an opposite direction of rotation of the handle releasing the shoes.

At the entrance or the left end of the apparatus (Fig. 3) within the compartment 25 of the adjustable frame 24 is a pair of feed rollers 55 and 5| and at the exit or right end, within the compartment 21, is a pair of rollers 52 and 53. The latter rollers are slightly larger in diameter than the rollers 50 and 5| and consequently have a greater peripheral surface speed than the rollers 55 and 5| since, as will be described presently, both pairs of rollers are driven at identical speeds. Thus the rollers 52 and 53, when the strip or card 2| is gripped by both sets of rollers, serve to maintain the strip under tension. Since the two sets of rollers are carried on the frame 24 within the comparments 25 and 21 by similar means, although in different horizontal planes for a purpose to be described hereinafter, the arrangement for supporting the rollers 50 and 5| at the entrance end of the apparatus will be described, it being understood that the following description also applies to the rollers 52 and 53.

Secured to opposite side walls of the compartment 25 within openings therein lare bearing blocks 54, in which are journalled in fixed bearing portions thereof opposite reduced ends of the roller 5|. Carried in openings formed in the blocks 54 are vertically adjustable bearing blocks 51, in which are journalled opposite reduced ends of the roller 50, the roller being adjustably yieldably urged toward the roller 5| by compression springs 58 bearing at opposite ends upon the blocks 51 and adjusting screws 59 threaded into the blocks 54. The strip or card 2| is advanced through the apparatus by the cooperating sets of feed rollers 5U and 5| and 52 and 53 at a predetermined constant rate such that the velocity and abrasive action of the grinding wheel I9 upon the card 2| does not retard the advance of the card. To insure a positive advancing action of both rollers of each pair upon the card 2|, each roller, as shown in Fig. 4, has fixed thereto a gear 60, the gear S of each pair of rollers being similar and in mesh and upon the rollers and 53 being rotated in a clockwise direction, it will be apparent that the rollers 55 and 52 will be rotated counterclockwise and at their adjacent peripheral portions a similar advancing action on the card 2|, as indicated by the arrows upon the rollers (Fig. 3) will be affected.

The rollers 5| and 53 are driven simultaneously and at the same velocity by means of a sprocket chain 6| (Figs. l and 2) which meshes with similar sprocket wheels B4 fixed to the rollers 5| and 53, the chain passing over idler sprocket wheels journalled on the frame 24 and thence around a sprocket wheel 66 secured to a shaft 61 journailed on a bearing bracket 68 fixed to the post 3|. Secured to the shaft 61 is a worm wheel 1| meshing with a worm wheel 12 fixed to a shaft 13, which is also journalled on the bracket 68. To the shaft 13 is secured a sprocket wheel 1li around which extends a sprocket chain 15, shown fragmentarily, which may be driven from a sprocket wheel attached to the output shaft of a speed reducing mechanism coupled to an electric motor, such mechanism and motor being preferably mounted on the xed frame |0. The electric motor and speed reducing mechanism, since they form no part ofthis invention are not believed necessary to a complete understanding thereof, have been omitted from the drawings for the sake of simplicity. During any necessary adjustment of the frame 24 with the attached post 3| and other parts upwardly or downwardly by means of the hand wheel 40 it will be understood that the sprocket wheel 14 and chain 15, which move with the post 3|, may rock about the xed axis of the sprocket wheel on the output shaft of the speed reducing mechanism (not shown), sufficient play being arranged in the sprocket chain 15 to permit this movement.

Referring particularly to Figs. 3 and 4, suitable strip or card guiding means comprising three separate units are indicated in general at 1G, 11 and 18, which are supported on the frame 24. Each of the guide units 16, 11 and 18 comprise spaced and united upper and lower plates, between which the strip or card 2| may freely pass in its advance through the apparatus. The guide unit 1B at the entrance end of the apparatus, referring to the left side of Fig. 3, extends through an opening in the wall of the compartment 25 and to a point intermediate and adjacent the feed rollers 55 and y5|, the lower plate extending appreciably t0 the left of the frame 24 to provide a table or apron upon which the strip or card 2| is first placed and then advanced inwardly toward the feed rollers 56 and 5|, which grip and ad- Vance it to the feed rollers 52 and 53. Between the feed rollers 5) and 5| and the grinding wheel I9 is arranged the guide unit 11 having the upper face of the lower plate thereof in the plane of the upper face of an irregular arcuate shaped member 16 mounted upon and secured to the cap plate 32, which forms a backing plate for supporting the advancing strip or card 2| during the grinding thereof by the opposed annular face 2] of the grinding wheel I9. The guide unit 11 extends from a point arranged in the plane of the guide unit 16 and adjacent the feed rollers 50 and 5|, through a slot in the wall between the compartment 25 and 26 and terminates in suitable spaced relation with the periphery of the rotating grinding wheel I9, the lower face of the upper plate being substantially in the plane of the lowermost point of the annular grinding face 20 of the wheel i9. Inclined from a point intermediate and adjacent the feed rollers 52 and 53, which are arranged slightly below the feed rollers 55 and 52, and extending to a point adjacent the inner periphery of the grinding wheel |9 and substantially in the plane of the guiding unit 11 is the guiding unit 18. At its left end (Fig. 3), the lower plate of the unit 18 rests on an irregular shaped shouldered portion of the backing plate 19 and in the plane of the upper face thereof, which is slightly inclined to meet it.

geom-ee The uppery plate ofi` the' uniti '|31- lies substantially' inthe Planeofthe upper: plate-or the unit Tlf and terminates adjacentV the? inner periphery of the grinding, wheelV I9: InV offset relation'iadl'acent the right side.` ofv the grindingfwheel I9 (Fig. 3), the upper and :lower platesvof=the unit 'lavare split'andfcarried b'etweengspa'ced adjacent ends or they plates and supportedlthereon are brushes eiland Sil offeltforother-suitable-material arranged in wiping relation withoppositelongitudinal faces ofthe-` advancing strip or card 2 I, which areI effectiveto prevent ground particles carried by the cardv from getting@betweenithe'V Particles brushed f from,

feed vrollers 52 and 53. the faces of the card'drop-into the bottom of-the compartment 26 through spaces 85 provided between guide plates. 85 which' space the upper' and lower guidev plates ofthe unit '88. The unitlSv extends through a'slot in the wallv between thev ing applied for. lubricating: and cooling during the grindingv operation,` andato flush and lcarry the ground particlesl off the' card 2| and theV annular grindingwheel face into the compartment 2S: A stream of water for similar'puru posesisalso sprayed'` through a -channelSZ in the cap plate 32and`against the lower surface of the grinding wheel |9at one side of the guideY unit 'i8 (Fig.v 2), within and adjacent that portion of the annular facel: ofthe wheel, which engages the card 2|; as shown in Fig. 3, the water being. carriedand directed-between the card '2l and the annular faceZll of the grinding wheel Channel 92 is supplied-with Water from a' lil. pipe 93 extending through the post- 3|,A to which is connected-'ai ilexiblesupplyfhoser Sit' (Figs. i and 2). Formed* in the-compartment 2t below the brushes 83v and 84- is an'aperturedconduit 95 for constantly spraying water across the upper surface of the bottomawall of the compartment, which serves to flush and carry the ground particles washed and-brushed into the compartment toward and into a `drairropening and conduit Qt at the left end of the compartment. For supplying the conduits 88 and 95 with water, ilexible supply hose S9 and |00, respectively, are conu nected thereto (Fig. 4).

As shown in Fig. 3, the annular grinding face 2B of the wheel I9 is ground with a slight bevel, its outer peripheral edge being in the plane of the advancing material and then risingv therefrom. This provides anrarcuate shaped relatively narrowperipheral line' of engagement thereof with the surface of the constantlyl advancing strip orcard 2|. In order to facilitate the maintenance of this lbevelledgrindingwheel face 2l), a dressing tool, indicated in general at lill (Fig. 2), is carried on the vertically adjustable frame '24. The tool mi 'comprises'a bearing member |92, which is secured to a surface |95 on the frame 24, the surface IDE being ground .to extend perpendicular to the bevelled grinding wheel face 2D and is formed with an opening to freely receive a holder |66, which is reciprocably carried in the bearing member |62 for movement parallel to the bevelled grinding Wheel' facel 211;. and=keyedfat- |08 ytoffthe memberf |02 to prevent itsrotation. Securechto thefholder: |06 is a diamond or otherfsuitablei tool |09?. which is arranged, when-the holder is freoiprocated to the rightV (Figr 2), to engage`Y the bevelled face 2|]` of thefrot'ating wheel.` ISL-and; in moving parallel thereto; to dress-it.` A pinion 1 H2, secured to a shaft ll'journalled'in` the member |02, engagingrack teeth |,I4formedonf the periphery of the holder |06; uponbeing ro-x tated clockwise, by a-handle Hxed-to the; shaftv H3, causes the tool |69 to advance acrossf the rotatingannular inclined grindingwheel face'- 2|l to dress it. ForA each dressingl operation ofi the grinding wheel face 20' when compensation; for wear thereon is toloeefected,- the verticallyadjustable frame 2111 ismicrometrically'raisedloy rotating the hand wheel 40 an amount sufficientiI to permit the diamond tool |99v to engage andj-i dress the face 20.

1t will be assumed thatbeiorethe apparatus is set in operation, the guide units l5, l';'|-and 'it for the particular thickness of` strip orrcard 2| to be ground have been arranged Ourthe-frame:

, 2li in proper relation to the sets 'offeed rollerspll7c and 5l and" E2 and 53, the: ba'ckingyplate*r 19,'. and the bevelled annular" faceI 2G, of-thesgrind-r ing wheel It, the latter beingA elected in-theL2 manner previously described.l by rotating the hand wheel do. Also, water'is being sprayed vfrom -f the apertured conduits 88 andV llfand-fftherchanw nel 92. After startingthe motor |-|to causethe: grinding wheel lil Yto bef rotatedinrthedirection of the arrow in diand'causing the driveY (noty shown) to the sprocket' chain 'ltobefset-in' mos tion andy thus rotating the feed" rollers inf the direction of the arrows in Fig` 3,' astriporf card blank 2| is placed on'theapron or lower guide plate extending fromtheguide unit'le and against aguide strip HS" by: th'e'operator.L Upon advancing the blank 2| to the feed rollers 5t and 5|, it will be fed'thereby and'through the guide unit 'il and between the left hand fpor tion of the rotating bevelled annular face Ell of the grinding wheel |9and the backin'g'platefl;

where it is ground'toa'predetermined:thickness:. As the ground blank continuesits-Sadvance, it," enters the inclined guideY lunit 7S;- isV advanced: past the brushes 33 andl; and is `guidedto the: feed rollers and 53 which, as'described' here-- inbeiore, have a slightly greater peripheralspeed than the rollers Eil and 5I.Y Byproviding this peripheral speed diferentialbetween the` two sets of rollers for' maintaining the blank' under tension for a great part of the grinding-` thereof, it has been found that, in grindingI the l longer strips, a more uniform grind-ingis effected.

What is claimed is:

1. An apparatus forgrinding strip material to a uniform thickness throughout its length and' breadth comprising a stationary base over which y the material may be passed, an abrasive wheel7 having a radially extending ring-shapedbevelled abrading surface, the outer peripheral edge of said surface being in the plane of the advancing material and then rising therefrom, means for'` guiding said material to a point adjacent the,4 outer peripheral edge of said wheel and between" said abrading surface and said base so that said abrading surface makes substantially an arcuate* line contact at said peripheral edge with' the ina-p terial, and means for flexing andguiding the` abraded material from a point adjacent the inner peripheral edge of said abrading surface and away from a diametrically opposite arc of said asozeee 'abrading surface whereby only a single continuous arc of said abrasive wheel is effective to abrade said material.

2. In an apparatus for grinding advancing strip material to a uniform thickness throughout its length and breadth, a grinding wheel rotatable about an axis arranged perpendicular to the direction of advance of the material at the point of grinding and having an annular bevelled grinding face, the outer peripheral edge of said face being in the plane of the advancing material and then rising therefrom, a backing plate disposed laterally of said axis for supporting the advancing material in predetermined substantially arcuate line contact with the outer peripheral edge of said face, and flexing and guiding means at each side of said backing plate for the material in its advance to and past said backing plate arranged to deflect the material after being ground from the plane of said face.

3. In an apparatus for grinding advancing strip material to a uniform thickness throughout its length and breadth, a grinding wheel rotatable about an axis arranged perpendicular to the direction of advance of the material at the point of grinding and having an annular bevelled grinding face shaped to make substantially an arcuate line contact at its external peripheral edge with the material, the external peripheral edge of said face being in the plane of the advancing material and then rising therefrom, a backing plate disposed laterally of said axis for supporting the advancing strip material in predetermined operative relation with one portion only of said face, and flexing and guiding means adjacent each side of said backing plate and the inner and outer peripheral edges of the grinding wheel for the material in its advance to and past said backing plate arranged to deflect the material after being ground from the plane of said face.

4. In an apparatus for grinding advancing strip material to a uniform thickness throughout its length and breadth, a grinding wheel mounted in a fixed position and rotatable about an axis arranged perpendicular to the direction of advance of the material at the point of grinding and having an annular bevelled grinding face, the external peripheral edge of said face being in the plane of the advancing material and then rising therefrom, a backing plate disposed laterally of said axis for supporting the advancing material in predetermined substantially arcuate line contact with the outer peripheral edge of said face, ilexing and guiding means at each side of said backing plate for the material in its advance to and past said backing plate arranged to deilect the material after being ground from the plane of said face, reciprocatory means for supporting said backing plate and said guiding means, and means for actuating said reciprocatory means to micrometrically position the same and thereby said backing plate and said guiding means relative to said face.

5. In an apparatus for grinding advancing strip material to a uniform thickness throughout its length and breadth, a grinding wheel rotatable about an axis arranged perpendicular to the direction of advance of the material at the point of grinding and having an annular bevelled grinding face, the outer peripheral edge of said face being in the plane of the advancing material and then rising therefrom, laterally of said axis for supporting the advancing material in predetermined substantially arcuate line contact with an ever-changing portion of the outer peripheral edge of said face, cooperating material advancing means arranged in different levels at opposite sides of said face, one of said advancing means serving to advance the material between said backing plate and the ever-changing portion of said grinding face, flexing and guiding means for the material arranged between said backing plate and the other of said advancing means for deflecting the material from the plane of said face and to said other advancing means, and means for actuating said advancing means.

6. In an apparatus for grinding advancing strip material to a uniform thickness throughout its length and breadth, a grinding wheel rotatable about an axis arranged perpendicular to the direction of advance of the material at the point of grinding and having an annular bevelled grinding face, the outer peripheral edge of said face being in the plane of the advancing material and then rising therefrom, plate disposed laterally of said axis for supporting the advancing material in predetermined substantially arcuate line contact with an ever-changing portion of the outer` peripheral edge of said face, cooperating material advancing sets of rollers arranged in diiferent levels at opposite sides of said face, one set of said advancing rollers serving to advance the material between said backing plate and the ever-changing outer peripheral edge portion of said face, flexing and guiding means for the material arranged between said backing plate and the other set of said advancing rollers for deecting the material from the plane of said face and to said other set of advancing rollers, said latter advancing set of rollers being slightly larger in diameter than said other set of rollers so that they have a greater peripheral surface speed than said other set of rollers, thus tending to advance the material at a faster rate of speed than that of said other set of advancing rollers whereby the material extending between said sets of rollers and while being ground is subjected to tension, and means for actuating said advancing sets of rollers.

ANTON J. BRUNNER. AUGUST WENNERBERG.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS 

